Radiant floor and wall hydronic heating systems

ABSTRACT

A hydronic heating system that has a boiler supplying hot supply water, a reservoir of cooler return water, a supply water line, a return water line and one or more heating loops through which water flows from the supply line to the return line, the heating loop including a heating element that is a length of tubing that conducts water from the supply to the return and is mounted in a wall or a floor of an area heated by said system by RFH or RWH has: a thermally conductive plate mounted in the area floor or wall, adjacent a surface thereof and means for holding the length of tubing in intimate thermal contact with the plate, so that the plate is heated by conduction of heat from the tubing and the plate has a radiating surface that radiates heat to the area. The plate with slot is provided as a modular piece and several such modular pieces are arranges in line attached to the sub-flooring for RFH, or the wall studs for RWH, for insertion of the length of tubing in the aligned slots thereof; and following such insertion, the installation is ready for a finishing floor or wall covering. Thus, RFH or RWH is installed &#34;dry&#34; (without wet concrete, cement or plasted) and can be accessed later by removing the finishing cover.

This application is a continuation of Ser. No. 08/207,950 filed Mar. 8,1994.

BACKGROUND OF THE INVENTION

This invention relates to hydronic heating systems for dwellings,offices, etc. and more particularly to such hydronic heating systemshaving heating loops that consist of tubing or pipes in the floor orwalls of a room that heat the floor or walls so that the floor or wallsheat the occupants and things in the room by radiation.

RADIANT FLOOR AND WALL HYDRONIC HEATING

Radiant floor heating (RFH) and radiant wall heating (RWH) aretechniques of heating rooms in a dwelling or commercial building forhuman and creature comfort. It is believed by many that radiant heatingis the ideal way to warm the human body. Europeans have revitalized amodern form of hydronic radiant floor heating in the last few decadesafter it had been out of use since the Romans first used warm air floorheating systems in their villas two thousand years ago.

Radiant heating warms the surfaces of a room: the floor, the walls, thefurniture, which become heat sinks, slowly giving off their warmth tothe cooler surroundings. People and creatues in the room then absorbthis heat as needed. It can be compared to walking barefoot on warmearth that has been heated by the rays of the sun when surrounding airtemperature is cool, however, as long as there is no breeze, one feelscomfortably warm. Furthermore, in a radiant heating system, the warmtemperatures are kept at floor level and radiate up wards; and, sincethere is no circulating air, there is not a hot pocket of air formed atthe ceiling level. With radiant floor heating, one actually experiencescooler temperatures at head level and warmer temperatures at foot levelwhich results in comfort and warmth.

In most western European countries, especially Germany and Scandanavia,hydronic radiant heating is the most popular technique of heating, notonly residential dwellings, but also commercial buildings.

Heating comfort is not the only advantage of hydronic radiant floorheating and these other advantages help to make the choice even moresensible. Some of the other advantages of hydronic RFH and RWH are:

1. Reduced heat loss of 20% to 50%, depending on the application;

2. Suitable for all types of hydronic heat sources from high temperatureboilers to low temperature heat pumps and solar water heaters, sincemost of these systems will operate at loop supply water temperatures of120° F. or less;

3. Ideal for hard to heat areas, especially high and voluminous spacesand large glassed-in living areas;

4. No air movement within the building is caused by the system and sothere are no recessed areas where dirt and dust can be trapped, therebyeliminating some dust and allergy problems;

5. No visible radiation units, thereby eliminating the need to workaround heating elements, and so wall space is not limited by heatingelements; and

6. Completely quiet and free of circulation and expansion andcontraction noises, making the system noiseless.

In the past, tubing materials, control devices and proper installationtechniques had not been perfected and so radiant heating was not used.However, the present reliability of controls, special installationtechniques, and, particularly the development of very strong flexibleplastic tubing, called PEX tubing, with its two decade record ofsuccessful installations embedded in cement floors, eliminates manycauses for concern.

High efficiency oil and gas fired boilers reach seasonal efficiencylevels of over 80% for conventional oil and gas boilers and over 90% forcondensing gas boilers. Every additional percentage point to be gainedby bringing flue gas temperatures into the condensing stage results inmore equipment and maintenance costs. Therefore, in the hydronic heatingsystem, there is a potential for fuel reduction in residential andcommercial buildings not only for new installations, but also forexisting systems. Such improvements can be accomplished using existingtechnology and available equipment and applying cost effectiveinstallation methods that afford short pay back periods. The mostdesireable benefits of this are increased heating comfort as well assignificant fuel reduction. Some of the existing technologies that canbe used to accomplish these improvements are:

1. Operate with continous circulation rather than intermittentcirculation by using state of the art weather responsive indoor/outdoorreset controls and mixing valves; thus separating the radiation systemfrom the boiler system for greater heating comfort and fuel reduction of10% to 35%.

2. Use large heat radiation surfaces in all the heated spaces, becausethe larger the heat emmission surfaces, the lower the heating mediumtemperature. This results in greater radiant heat output and lessconvection heat output and avoids using large surface steel, cast iron,or aluminum radiator panels. For every 3° F. reduction of seasonal meansupply water temperature, there is approximately 1% fuel reduction. Inaddition, the lower the radiation surface temperature, the higher is thelevel of human health comfort, because there is less convective airmovement.

3. An RFH space allows a reduction of 3° F. to 4° F. in ambient airtemperature to be maintained without any loss of heating comfort andavoids heat stratification in ceiling areas and heat loss through theroof.

4. Hydronic heating permits domestic hot water (DHW) production using alarge efficient heat exchanger for producing and storing DHW, called anindirect fired DHW tank.

5. Time-cycling and outdoor reset controls are well developed andavailable.

Floor heating and snow melting installation techniques of hydronicheating systems for heating the rooms in a dwelling or commercialbuilding are used widely in Europe and to a lesser extent in the UnitedStates. In these systems, water heated in a boiler is distributed toheating loops of tubing in the dwelling that carry the heat byradiation, conduction and convection to the rooms in the dwelling. Acommon technique provides a boiler hot water supply feeding the supplyheader of the heating loops and the boiler water return to which thereturn header of the heating loops connects. The return water is heatedin the boiler and sent out again as hot supply water, and so the wateris cycled through the essentially closed system. One or more water pumpsin this system keep the water flowing and valves control water flowrates through the loops depending on demand.

A heating loop may include several heating elements like wall mountedradiators and/or baseboard finned tubing that are the principal heatexchangers of the loop, or the tubing itself may be the principal heatexchanger of the loop. In the latter case the tubing is usually buriedin a layer of concrete that forms the floor of a room and so the tubingheats the concrete slab, which is the floor. The concrete that thetubing is buried in is a special kind for the purpose and the heatexchange is principally by conduction and radiation to the concrete,which in turn heats the room by some conduction and convection, butprincipally by radiation. Hence, this type of heating is called RadiantFloor Heating (RFH). Similarly, the tubing is sometimes mounted in awall embedded in a layer of concrete and this is called Radiant WallHeating (RWH).

PLASTIC TUBING HEATING LOOP

In such RFH and RWA systems and other hydronic heating systems usingwall radiators and/or baseboard finned tubing elements, the supply watertemperature from the boiler must be controlled so that it does notexceed certain limits that are substantially lower than the usual boilersupply water temperature. There are several reasons for this: the flooror wall must not be uncomfortable hot; and where the tubing is plastic,the water temperature for some plastic materials must not exceed about140° F., although good quality "cross-linked" polyethylene tubing cancarry water at temperature in excess of 140° F. without anydeterioration of the tubing or the tubing oxygen barrier.

The design criteria of plastic tubing for RFH and RWH systemapplications is determined by a number of important factors to insure anabsolutely safe and reliable tubing. The most important design criteriarequirements are:

1. High resistance to temperature aging for water temperatures up to200° F.

2. High resistance to stress cracking.

3. High resistance to chemical solvents (water additives, antifreezesolutions, concrete additives).

4. Lowest possible linear thermal expansion.

5. High tensile strength.

6. High form stability.

7. High resistance to abrasion.

8. High resistance to deformation.

9. Dimensional tube tolerances.

9. Internal and external tube wall smoothness.

10. Behavior during long term internal pressure creep test which takesinto account the temperature-dependent aging behavior of the pipematerial at water temperatures up to 200° F.

Many of these requirements are dictated by the usual practice ofembedding the tubing in a layer of concrete. They are design criteriathat are outlined and specified in the ASTM standards (American Societyfor Testing and Materials), and DIN (German Industry Standards). Many,if not all of these design requirements be achieved while stillretaining a flexible and workable plastic tubing (pipe) as an endproduct. That tubing is called PEX, which is short for "PolyetheleneCross-Linked". PEX has been synonomous with plastic heating pipe in manyEuropean countries for several decades and has a track record that hasmade it the plastic tubing of choice for hydronic heating applications.Long term bench tests, which simulate 30 years of continuous use, inaddition to accelerated testing which projects pipe performance well inexcess of 30 years has confirmed the excellent long term real servicelife track record of PEX. Crossed-linked polyethylene tubing is now,after 20 years of use and improvements, the most widely accepted pipematerial in the European plumbing industry for both heating and plumbingapplications.

Plastic Tubing and Cross-Linking

The molecules of any plastic material tend to slip and slide over oneanother fairly freely. As ambient and water temperatures rise, theplastic material softens and finally melts. This thermal oxidation ofplastic material is a long term aging process which will eventuallyresult in pipe failure.

To combat this premature aging the molecules within the tubing arerealigned in order to give greater stability to the material itself. Thecross linking process takes place within the molecular structure of theplastic material. The most common thermoplastic materials currentlybeing used for heating and plumbing pipe, often referred to aspolyolefin materials are: Polyethylene (PE); Polypropylene (PP); andPolybuten (PB)(generic term for polybutylene). Among this family ofpolyolefin plastics, only Polyethylene has been determined to have themolecular structure which lends itself perfectly to the cross linkingprocess.

"Un-cross-linked" polyethylene tubing, as it leaves the extruder whereit receives its basic pipe dimension and wall thickness, is composed oflong hydro-carbon string molecules forming a loosely held together arrayof hydrogen and carbon atoms which can be compared to a beaded curtainswaying in a breeze. This is basically the molecular composition of thepolyethylene tubing which is available at any hardware store and issuitable only for non-critical applications such as drainingcondensation from an air conditioning unit or syphoning gasoline fromfrom a. A material, in this form, is unsuitable for heating and plumbingapplications. Within a relatively short period of time the pipe materialfatigues under the stress of water temperature and pressure as well astemperature cycling and the beaded curtain would splits open withoutresistance. By cross-linking those beads (hydro-carbon stringmolecules), forming cross-connections which are referred to ascross-linking bridges, the string molecules form a three dimensionalnetwork of hydro-carbon molecules. The beaded curtain becomestransformed into a fishing net with strength and stability.

The previously non-applicable polyethylene pipe has been trans formed,after cross-linking, into a completely different material with all thedesired characteristics we demand for a heating or plumbing pipe. Afterthe crosslinking of the PE tubing, its molecular mobility is severelyimpeded by the cross-linking bridges between the string molecules. Thematerial does not flow or melt and its form becomes stable against heat.The material holds its shape at all temperatures, even exposed to blowtorch temperatures until it chars or burns. The thermoplastic has beentransformed into a thermoset material by cross-linking, eliminating themelting point or liquid phase of the material.

Cross Linking Techniques

There are basically two types of PE raw materials in use: Low to mediumdensity (LD or MD PE) and High density (HD PE). Low to medium densitypolyethylene "SOFT PE" has a multibranch string molecule shape whichallows a lower to medium density formation of string molecules withinthe pipe material.

High density polyethylene has a linear string molecule shape with onlysmall stumps of branches, which allows for a higher density formation ofstring molecules within the pipe material.

The material density affects the physical properties of the pipematerial. HD PE or "HARD PE" has a higher resistance to stress crackingand chemical solvents, higher tensile strength, higher resistance todeformation and is less permeable to oxygen

Chemical Cross-linking includes: Peroxide Cross-linking; SilanCross-linking via Dow Corning Method; and AZO Cross-Linking. Threemethods of Peroxide Cross-Linking are the Engel, PAM and DAOPLASTmethods.

Mechanical Cross-linking is Electronic Cross-linking by a Cross-LinkingHigh Energy Electron Beam

The various chemical cross-linking methods use chemical agents which areadded to the PE base resin in order to form cross-linking bridgesbetween the PE string molecules. The only practiced mechanicalcross-linking method uses no chemical agents, instead, utilizes the highenergy of an electron beam accelerator to form a three dimensionalcross-linking network between the PE molecules.

Among the various chemical methods only two types are commonly used forheating pipe production: The Engel and Silan method. The Engel method,named after its inventor, uses a cross-linking agent (peroxide) and heatstabilization agents which are mixed into the PE resin. The mixture isthen compressed under high pressure in a "pre-molten" state and fedthrough the extrusion die, where the actual cross-linking process takesplace. This is a "press-sintering" process which achieves pipe extrusionand molecular cross-linking during one extrusion process.

The Silan method uses a mixture of two compounds with a mixing ratio of95 to 5 parts. One compound consists of PE-resin and cross-linkingagents as well as other additives. The second compound consists ofPE-resin and a catalyst. After mixing both compounds, the pipe isextruded conventionally. The cross-linking reaction is triggered afterextrusion by exposing the extruded coil to moisture such as steam orwater. Most other chemical methods are variations of either the Engel orSilan method.

The electronic or mechanical cross linking method does not use anychemical means to achieve cross-linking bridges between thePE-molecules. The basic PE-resin is first extruded to give the pipe thebasic required dimensional shape, then coiled up and fed through a highenergy electron accelerator which exposes the extruded pipe material tothe enormous energy of an electron beam. The energetic electrons strikethe PE-molecules at or near a carbon/hydrogen bond, releasing enoughenergy to the molecule to break that bond, setting the hydrongen atomfree which diffuses out of the pipe in the form of hydrogen gas duringthe process. A large percentage of carbon atoms have then lost theirhydrogen atom partner leaving the parent molecule in an excited state,able to form a new bond with another adjacent carbon atom without ahydrogen partner (called a free radical). These new carbon to carbonbonds are the desired cross-linking bridges which form a threedimensional network among the PE string molecules.

Electronic cross-linking is the oldest known method of creating PEX.Over three decade ago, U.S. Companies applied this method to manufactureprimarily cable enclosures including those used for undersea cables.This method was then adopted by German manufacturers for the productionof heating and plumbing pipes.

Oxygen Diffusion

A closed loop hydronic heating system will cause an oxygen poor watercondition after the initial filling of the piping system. Oxygendepleted water (dead water) in an oxygen tight closed piping system isan effective and inexpensive heat transfer medium. The benefit of oxygendepleted water is its non-corrosiveness to system components, piping,valves, pumps, boilers, etc. However, this generated "oxygen vacuum"within a closed piping system causes a very high affinity in the systemwater for oxygen enrichment. This means that the generated oxygen vacuumin the system will absorb outside oxygen through any means possible.

In a steel or copper piping system the only source of oxygen permeationis through leaking fittings, valves, air vents, and above all,improperly sized expansion tank equipment. Copper or steel tubing itselfis absolutely oxygen tight. However, that is not the case with plasticor rubber tubing. In recent years it has been discovered in Europe,after enormous corrosion and subsequent sludging problems developed insystems utilizing oxygen permeable plastic tubing in "closed systems",that plastic tubing allowed enough oxygen permeation through the pipewall to cause corrosion in the system.

Subsequently, a special oxygen diffusion test for plastic tubing wasdeveloped to determine the amount of oxygen penetrating the tubing. Thechemically bound oxygen (no visible air bubbles) in the system waterentering through the pipe walls creates an extremely aggressive watercondition, corroding not only ferrous materials but also copper, brassand plastics as well. The tests revealed that the rate of oxygendiffusion is directly related to the system water temperature--thehigher the water temperature, the higher the rate of diffusion which ismeasured in milligrams per liter per day.

The German Industry standards (DlN) have determined that an oxygendiffusion rate of 0.1 mg/liter/day or less at a water temperature of104° F. (40° C.) in plastic tubing is considered a safe level to preventoxgen corrosion in heating system components. For comparison: The amountof 5 milligrams of oxygen per liter per day caused by oxygen diffusionthrough the pipe wall is equivalent to completely draining the heatingsystem and refilling it with fresh water every other day during theheating season.

In order to eliminate the serious problems of oxygen diffusion on closedloop heating systems with plastic pipe, oxygen diffusion barriers havebeen developed. These barriers are usually applied to the exterior ofthe pipe. Each pipe manufacturer has its own method and process forapplying this barrier. The main criteria for these barrier applicationtechniques are the operating water temperatures of the intended pipeusage.

An acceptable alternative to oxygen diffusion barriers is the usage ofsystem separation by means of stainless steel heat exchangers thatseparate the plastic distribution system from the heat source andmechanical components.

Oxygen diffusion is obviously no issue for plastic tubing intended foruse on open hot and cold domestic hot water systems where oxygen ispresent at high concentrations in any case.

Low Temperature vs High Temperature Operation

The hydronic heating loop supply water temperature could be maintainedlow and so avoid the problem of tubing aging, by simply operating theboiler at a lower water temperature. However, that can cause flue gascondensation on the boiler water heat exchanger. For example, the fluegas due point can be as high as 140° F. and so to avoid flue gascondensation it is preferred that the boiler supply water temperature benot less than 140° F.

In hydronic heating systems subject to such water temperaturelimitations, where the boiler is powered by burning fossil fuels, theboiler water supply temperature is usually well above 140° F. and oftenat about 190° F. to 200° F., and so the boiler supply temperature mustbe stepped down before it is fed to the heating loops.

A suitable system for reducing and controlling the supply watertemperature is described in my U.S. Pat. No. 5,119,988, issued Jun. 9,1992, entitled "Hydronic Heating Water Temperature Control System. Inthat patent a three-way, modulated diverting or by-pass valve isprovided in the return line to the boiler, between the heating loopreturn header and the boiler return. The diverting valve has one inputand two outputs. The input is from the heating loops return header, thefirst output is to the boiler return line and the second output is tothe boiler supply line. The diverting valve diverts some of the coolerreturn water to the hot supply water to reduce the temperature of thesupply water feeding the heating loop supply header. Thus, the supplywater is diluted with return water, lowering the temperature of thesupply water directly from the boiler. The diverting valve is amodulated valve and the temperature of the supply water flowing to thesupply header is detected and used as a feedback control signal tomodulate the valve.

SUMMARY OF REQUIREMENTS FOR RPH AND RWH

Thus, the boiler must be operated at a sufficiently high watertemperature (over 160° F.) to avoid flue gas condensing, the supplywater temperature to the heating loops must be reduced to no more than110° F. so that the heated floor or wall is not uncomfortable to standon or touch, the heating loop tubing must be PEX quality or better andhave an oxygen barrier and the tubing must be sufficiently flexible thatit can be inserted in place with ease and not require special skills andequipment to install.

Heretofore, these requirements have been met using a hydronic heatingsystem having supply water temperature control such as described in saidU.S. Pat. No. 5,119,988, or other suitable supply water temperaturecontrols, to feed one or more heating loops of PEX tubing that isembedded in a layer of special concrete three to six inches thick thatserves as the floor or wall of a room to provide RFH or RWH heat in thatroom.

Installation of the PEX tubing embedded in concrete requires specialskills and tools and is relatively expensive. Also there must besuitable support structure as the concrete adds considerable weight.This technique of installing the tubing in wet concrete or cement issometimes called a "wet" installation and requires special equipment andworking skills to hold the tubing in place, and in the case of RFH, pourthe wet concrete to cover the tubing by an inch or more and finish theconcrete surface when it sets. For a wall installation, special skillsare required to spread to spread a special wet cement or plaster mixover the tubing that has been attached to the wall and then finish thewall, usually with a wet white plaster mix. These "wet" installationsdepend upon the direct conduction of heat from the tubing into theconcrete or plaster, raising the temperature of the concrete or plaster,which in turn radiates heat into the room. For such RFH and RWHinstallations, radiation into the room is entirely dependent upon theheat from the tubing flowing by conduction to the concrete or plaster.For such RFH installations, there is often no adequate thermal barrierunder the concrete, particularly when the concrete floor is supporteddirectly by gravel, sand or earth.

The thermal mass of the cured cement, concrete or plaster in theseinstallations makes the response time of the hydronic heating systemslow. The cement, concrete or plaster is a large heat sink and until thetemperature of this mass is raised, there is no increase in heat flowinto the heated area. This large thermal mass also results inoverheating, because the system tends to deliver more heat than isrequired to meet the demand, unless the control system is sophisticatedand programmed for the particular area that is heated.

The PEX oxygen barrier tubing, or its equivalent, is required for theseinstallations to insure that the PEX tubing will not fail within thelife expectancy of the building it is installed in. Inferior qualitytubing fatigues under the stress of the water temperature (even water at110° F.) and pressure and splits, like un-cross-linked polyethylenetubing and without a suitable oxygen barrier, oxygen diffusion occursand the system components that contain the water corrode. When suchfailures occur, the concrete floor or wall in which the tubing isembedded must be broken up and the entire loop replaced.

Clearly, there is a need to provide hydronic RFH and RWH with all of thebenefits thereof without embedding the loop tubing in concrete, cementor plaster, or the like, in new construction and in old construction.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hydronic heatingsystem in a building wherein the system heating elements include tubingin the floor and/or the walls of the building in a "dry" installation(without embedding the tubing in concrete, cement, plaster, or thelike).

It is another object to provide such a system that radiates heat intothe heated area more quickly than an equivalent "wet" installation.

It is another object to provide such a system wherein overheating, asoccurs in an equivalent "wet" installation, is less likely to occur.

It is another object to provide such a system that is relatively lessexpensive than prior hydronic RFH or RWH systems of equivalent capacityand which avoids some of the limitations and disadvantages of the priorsystems.

It is another object to provide such a system for which installation ofthe RFH or RWH tubing heating elements is relatively less expensive thanfor prior hydronic RFH or RWH systems of equivalent capacity and whichavoids some of the limitations and disadvantages of the prior systems.

It is another object to provide such a system for which installation ofthe RFH tubing heating elements is on top of the rough flooring of aroom.

It is another object to provide such a system for which installation ofthe RFH tubing heating elements is below the rough flooring of a room.

It is another object to provide such a system for which installation ofthe RWH tubing heating elements is over the studs of a wall in a room.

It is another object to provide such a system for which installation ofthe RWH tubing heating elements is between the studs of a wall in aroom.

It is another object to provide such a system for which thermalconduction and radiation from the RFH or RWH tubing heating elements isincreased substantially by radiating surfaces in direct thermal contactwith the tubing, and forming part of the installation.

It is another object to provide such a system for which the installedRWH or RWH tubing heating elements can be reached for repair by removingno more than a "dry" finished floor or wall covering that is installedover the elements.

It is another object to provide such a system for which the RWH or RWHtubing heating elements can be installed on top of existing finishedfloor or wall surfaces.

It is another object to provide such a system for which the RWH or RWHtubing heating elements and installation parts thereof are the same forRFH and RWH.

It is another object to provide such a system with boiler supply watertemperature control that is satisfactory to avoid feeding excessivelyhigh temperature boiler supply water to the system RWH or RWH tubingheating elements.

It is another object to provide such a system with boiler supply watertemperature control that is satisfactory to avoid feeding excessivelyhigh temperature boiler supply water to the system RWH or RWH plastictubing heating elements.

It is another object to provide such a system with boiler supply watertemperature control that is satisfactory to avoid feeding excessivelyhigh temperature boiler supply water to the system heating loops andalso avoid operating the boiler at a water temperature that is likely tocause flue gas condensation in the boiler.

Embodiments of the present invention have application to a hydronicheating system that has a boiler supplying hot supply water, a reservoirof cooler return water, a supply water line, a return water line and oneor more heating loops through which water flows from the supply line tothe return line, the heating loop including a heating element that isthe length of tubing that conducts water from the supply to the returnand is mounted in a wall or a floor of an area heated by said system byRFH or RWH. The invention includes a thermally conductive plate mountedin said area floor or wall, adjacent a surface thereof and meansincluding a compliant thermally conductive filler material for holdingthe length of tubing in intimate thermal contact with the plate, so thatthe plate is heated by conduction of heat from the tubing and the platehas a radiating surface that radiates heat to the area. In the firstembodiment described herein, the plate is between the tubing and thefloor or wall surface and is held against the plate by holding pieces(sleepers) that hold the plate against the floor or wall and also holdthe tubing against and longitudinally along the plate and in intimatethermal contact with the plate by compliant thermally conductive fillermaterial. In the second embodiment described herein, the tubing isbetween the plate and the floor or wall surface and there is alongitudinal slot in the plate that serves as the tubing holding meansand is an integral part of the plate, so that the plate substantially"wraps" around the tubing and in intimate thermal contact with the plateby compliant thermally conductive filler material; and holding pieces(sleepers) hold the plate against the floor or wall and also support anddefine the slot in the plate.

In preferred embodiments, the plate and the tubing holding means,including the holding pieces (sleepers) are assembled to form a modularpiece or modular unit; and several such modular pieces are arranges inline attached to the sub-flooring for RFH, or the wall studs for RWH,ready for insertion of the length of tubing in the aligned holding meansthereof and in intimate thermal contact with the plate by compliantthermally conductive filler material; and following such insertion, theinstallation is ready for a finishing floor or wall covering. Thus, RFHor RWH is installed "dry" (without wet concrete, cement or plasted) andcan be accessed later by simply removing the finishing cover.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an RFH installation showing the first embodimentin an exploded view revealing the tubing, heat conduction and radiationplates that are in intimate thermal contact with the tubing and holdingpieces (wood strapping) that holds the assembly of tubing and radiationplates against the under side of the rough flooring that is on top ofthe floor joists of a room in a typical wood frame building;

FIG. 2 is an end view of the parts shown in FIG. 1 and is also anexploded view of the parts;

FIG. 3 is an end view of the parts shown in FIG. 1 showing the partsinstalled;

FIG. 4 is a further enlarged end view showing the assembly of tubing,heat transfer plate and holders;

FIG. 5 is a perspective view of the assembly of heat transfer plate andholder of the first embodiment providing a modular piece or modular unitof modular size;

FIG. 6 is a much enlarged end view of the modular piece of the firstembodiment showing the assembly of tubing, heat transfer plate andholder; and showing a compliant caulking or epoxy adhering the tubingagainst the plate in intimate thermal contact therewith between theholder pieces;

FIG. 7 is a diagram of an RFH installation showing the second embodimentin an exploded view revealing the tubing, heat conduction and radiationplates that are in intimate thermal contact with the tubing and holdingpieces, similar to the view of the first embodiment shown in FIG. 1;

FIG. 8 is an end view of the parts of the second embodiment shown inFIG. 7 and is also an exploded view of the parts;

FIG. 9 is an end view of the parts of the second embodiment shown inFIG. 7 showing the parts installed;

FIG. 10 is a top view of the RFH showing the floor joists with the roughflooring removed and shows the positions of the parts of eitherembodiment and illustrates a technique of feeding the tubing from oneend of the floor through chases in the floor joists to one after anotherof the spaces between floor joists;

FIG. 11 shows a typical wood frame construction on a concrete foundationincluding floor joist, rough flooring, wall plate and wall stud as anaid to understanding structures of the present invention;

FIGS. 12 and 13 are enlarged end and top views, respectively, of an RFHinstallation of the first embodiment under the rough flooring showingthe assembly of tubing, heat transfer plate and plate holder, the topview being taken below the rough flooring;

FIG. 14 is a further enlarged end view of the second embodiment showingthe assembly of tubing, heat transfer plate and holder;

FIG. 15 is a perspective view of the assembly of heat transfer plate andholder of the second embodiment forming a modular piece in a modularsize;

FIG. 16 is a much enlarged end view of the assembly of tubing, heattransfer plate and holder of the second embodiment, showing a compliantthermally conductive filler material, such as caulking or epoxy adheringthe tubing in a recess in the heat transfer plate in intimate thermalcontact therewith;

FIGS. 17 to 19 show variations of the same structure revealed in FIG. 16with straight or tapered walls defining the recess in the heat transferplate that accommodates the tubing, all including a compliant thermallyconductive filler material around the tubing providing intimate thermalcontact with the plate;

FIG. 20 shows a variation of the same structure revealed in FIG. 16 withtapered walls defining the recess in the heat transfer plate thataccommodates the tubing, compliant thermally conductive filler material,such as caulking or epoxy in the recess covered by a peel-off strip andthe tubing positioned for insertion into the recess after the peel-offstrip is removed;

FIG. 21 is an enlarged end view of an RFH installation on top of therough flooring showing several modular assemblies of tubing, heattransfer plate and plate holder (modular pieces), arranged side by sideon the rough flooring;

FIG. 22 is a perspective view of the floor of a room showing several ofthe modular assemblies of different kinds, arranged side by side and endto end on the rough flooring of the room;

FIGS. 23 and 24 are perspective views of the several modular pieces ofdifferent kinds, that can be arranged as shown in FIG. 22;

FIG. 25 is a front view of a RWH installation showing the wall soleplate, studs and top plate with several of the modular pieces ofdifferent kinds, such as shown in FIGS. 23 and 24, arranged side by sideand end to end on the studs, providing a horizontal arrangement ofseveral passes of the tubing across the studs and ready for covering bya finished wall covering;

FIGS. 26, 27 and 28 are enlarged side views of the wall, taken as shownin FIG. 25, showing the wall studs, modular pieces of different kindsattached (nailed) to the studs, from the center line of a stud to thecenter line of another stud and a finished wall covering on top of themodular pieces;

FIG. 29 is a front view of another RWH installation showing the wallsole plate, studs and top plate with several of the modular pieces ofdifferent kinds, such as shown in FIGS. 31 to 36, arranged side by sideand end to end on the studs, providing a vertical arrangement of severalpasses of the tubing up and down between the studs and ready forcovering by a finished wall covering;

FIG. 30 is an enlarged side views of the wall of, taken as shown in FIG.29, showing the wall studs, modular pieces of different kinds attached(nailed) to the studs, from the center line of a stud to the center lineof another stud and a finished wall covering on top of the modularpieces;

FIGS. 31 to 36 are views of the several modular pieces of differentkinds, that can be arranged as shown in FIG. 30;

FIG. 37 is a front view of yet another RWH installation showing the wallsole plate, studs and top plate with several of the modular pieces ofdifferent kinds, such as shown in FIGS. 31 to 36, arranged side by sideand end between the studs and recessed into the space between the studs,providing a vertical arrangement of several passes of the tubing up anddown between the studs and ready for covering by a finished wallcovering; and

FIG. 38 is an enlarged top view of the wall of, taken as shown in FIG.37, showing the wall studs, modular pieces of different kinds recessedon brackets that are attached (nailed) to the studs and notches in thestuds to accommodate the tubing passing from one recessed space betweenstuds to the next recessed space between studs.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION RFH--TUBING UNDER THESUB-FLOOR First Embodiment

FIG. 1 is a diagram of an RFH installation showing the first embodimentof the invention herein in an exploded view. The hydronic heating systemtubing 1 is part of a heating loop of the system and, in particular,part of an RFH heating loop of the system. The hydronic heating system(not shown) preferably has supply water temperature control, such asdescribed in the above mentioned pending U.S. patent application Ser.No. 545,399. The tubing is held against several lengths of heatconduction and radiation plates, such as 2 and 3. It is held betweenholding pieces 6 and 7, herein called sleepers, that may be woodstrapping, so that the entire length of the tubing intended to give offheat to the floor is in intimate thermal contact with the plates, end toend, along the length of the tubing.

To mount the assembly of plates, holding pieces (sleepers) and tubing tothe underside of the sub-flooring, as shown in FIGS. 2 and 3, the tubingis held against the plates, which are held firmly against the undersideof the sub-flooring 70 of a room, the sub-flooring being supported byfloor joists, such as floor joist 71. The plates 2 and 3 may be stapled,nailed or otherwise firmly attached to the underside of thesub-flooring. Then the tubing is mounted against the plates so that thetubing and the plates are in intimate thermal contact. Holding pieces 6and 7 hold the plate against the underside of the sub-flooring and thetubing is sandwiched between the holding pieces in space 4. The holdingpieces may be wood strapping and the entire assembly 10 of tubing 1,plates 2 and 3 and strapping pieces 6 and 7 are stapled or nailedthrough the strapping and plates to the bottom of the sub-flooring.

Second Embodiment

FIGS. 7, 8 and 9 show the second embodiment in diagrams similar to FIGS.1, 2 and 3, respectively. Here, the tubing 21 is between thesub-flooring and the plates 22 and 23 and is inserted into accommodatingslots 24 and 25 in those plates so that the entire length of the tubingintended to give off heat to the floor is inserted in the slots, end toend along the length of the tubing. The shape of the slots and the sizeof the tubing are such that the tubing is in intimate thermal contactwith the plates.

At mounting, as shown in FIGS. 8 and 9, the tubing, held by the plates,is held firmly against the underside of the sub-flooring (roughflooring) 70 of a room, the sub-flooring being supported by floorjoists, such as floor joist 71. The plates 22 and 23 may be stapled,nailed or otherwise firmly attached to the underside of the sub-flooringso that the tubing and the plates are in intimate thermal contact withthe underside of the sub-flooring. Holding pieces 26 and 27 may be woodstrapping and the entire assembly 30 of tubing 1, plates 22 and 23 andstrapping pieces 26 and 27 may be stapled or nailed through thestrapping and plates to the bottom of the sub-flooring.

Installation Procedure

Typical wood frame construction as done widely throughout the U.S. isshown in FIGS. 1 to 3 and 7 to 11 and in other figures in thisapplication. As shown in FIG. 11, the wood frame is erected on aconcrete foundation 72 and includes a sill 73 on which the floor joists71 rest, usually spaced sixteen inches on center. The outside ends ofthe joists are covered by outside plate 74 and the sub-flooring that isusually one inch boards or a heavy grade of plywood is nailed on top ofthe joists and end plate. The walls such as outside wall 75 is erectedon top of the sub-flooring.

Installation of each radiant heating assembly of the second embodimentof tubing, plates and strapping to the underside of the sub-flooring mayproceed as follows:

(a) Space the plates end to end along the tubing 1/4" apart;

(b) Cut strapping pieces 26 and 27 to exact length of the several plates22 and 23, end to end along the tubing 1;

(c) Sandwich tubing and heat transfer plates tightly between strappingsand the sub-flooring. (d) Force the plates onto the tubing so that thetubing snaps into the plates grooves;

(e) Staple one side of each plate to the sub-flooring while pushing ittightly against side of the adjacent floor joist;

(f) Push the plates with the strapping firmly against the tubing; and

(g) Fasten the strapping 26 and 27 over the plates by nailing, staplingor with screws into the underside of the sub-flooring.

Before installation of each assembly of tubing, plates and strapping tothe underside of the sub-flooring between adjacent floor joists (inadjacent floor joist bays), the tubing is pulled from a coil 76 of thetubing as illustrated in FIG. 10. The procedure is as follows:

(1) Pull the outside end of the tubing from the coil 76 and insert itthrough one after another pipe chase holes 77 in the floor joists fromthe near joist bay 78 to the far joist bay 79;

(2) Form a loop la of the tubing in the far bay 79 and insert the end ofthe tubing back through the chase holes 77 and pull the end from thechase hole that leads into the near bay 78, all of the way to thehydronic heating system supply header 85 and connect it to the a loopfitting thereof;

(3) Pull tubing loop la from the coil 76 and assemble each length ofthat loop with the plates, like 22 and 23, and the strapping, like 26and 27, to the underside of the sub-flooring;

(4) Pull the next loop 1b from coil 76 into the next bay 30 and assembleeach length of that loop with the plates, like 22 and 23, and thestrapping like 26 and 27, to the underside of the sub-flooring;

(5) Continue this procedure in bay after bay to and including the nearbay 78;

(6) Then, either pull the tubing off of the coil to the next floor ofthe hydronic heating system RFH loop and repeat this procedure, or, ifthe floor completed is the last or only floor of the loop, pull thetubing to the hydronic heating system return header 84 and connect it tothe loop fitting thereof to complete the installation; and

(7) Then insulate each bay with six inches or more of fiber glass matbetween the joists.

TUBE HOLDING MODULAR PIECES First Embodiment

A configurations of a module piece, which is an assembly of a heatingplate, like plates 2 and 3, and pieces that serve the functions of thestrapping pieces 6 and 7 in FIGS. 1 to 3, are shown in FIGS. 4 to 6. Atypical modular piece of this first embodiment, denoted 10a, is shown inFIG. 5. It is composed of two lengths 16 and 17 of plywood, particleboard or other rigid material, about the same thickness as the outsidediameter of the tubing it is assembled with. The two lengths 16 and 17of holder pieces (herein called sleepers) hold the heat conduction andradiation plate 12 against the underside of sub-flooring 70 and providea tubing containment space 14, the length thereof for holding the tubing1 against the plate.

As shown in FIG. 4, the tubing containment space 14 is the space betweensleeper pieces 16 and 17 and is closed on one end (the top end in thisFigure) by the plate and so the tubing must be inserted into this spacefrom the other end of the space (the bottom end in this Figure). Thus,the open end of the tubing containment space 14 is separated from thesub-flooring by the plate whether mounting is to the underside of thesub-flooring, as shown in FIGS. 1 to 4, or to the top side of thesub-flooring in essentially the same manner as shown and described withreference to FIGS. 21 and 22. When this first embodiment is mounted tothe top side of the sub-flooring, the plate is still between thesub-flooring and the tubing.

The plate is made of highly thermally conductive material such asaluminum, copper or steel. For example, it can be made of a relativelythin sheet of 0.008 guage, 3003 alloy aluminum; and is attached tosleepers 16 and 17 by a suitable glue or epoxy. Plate 12 can also bemade of heavier thermally conductive material so that it conducts heatfrom the tubing more readily.

For installations in wood frame construction where the spacing betweenfloor joists and between wall studs is 16 inches cn center, the modularpiece size is made in consideration of that usual joist and studspacing. For example, for the under floor installation shown in FIGS. 1to 3, two modular pieces must fit side by side in a bay between floorjoists and the bay width is about 141/2 inches. Therefore, the preferredwidth of the module piece is less than half of that, or between 6 and 7inches. The length of the modular piece is preferably a whole multipleof 16 inches and preferably 32 or 48 inches.

The inside edges of the sleeper pieces define the space 14 into whichthe tubing is inserted and held against the plate. Those edges 18 and 19are preferably beveled as shown in FIG. 6. The purpose of the bevel isto taper the space 14 so that it becomes wider toward the plate. Thus,the tubing must be forced into the space from the open side thereof andonce forced into the space is held firmly therein against plate 12. Thetubing is further held securely in space 14 in intimate thermal contactwith the plate by an epoxy material 20, as is described furtherhereinbelow.

Second Embodiment

Several configurations of a modular piece of the second embodiment,which is an assembly of a heating plate, like plates 22 and 23, andholding pieces that serve the functions of the strapping pieces 26 and27 in FIGS. 7 to 9, are shown in FIGS. 12 to 20. A typical modular piece30a of this second embodiment is shown in FIG. 15. It is composed of twolengths 31 and 32 of plywood, particle board or other rigid material,about the sane thickness as the outside diameter of the tubing it is tobe installed with. The two lengths 31 and 32 (herein also calledsleepers) support the heat conduction and radiation plate 33, which hasa longitudinal slot 34 the length thereof that fits snuggly (or snaps)around the RFH loop tubing at the installation.

As shown in FIG. 14, the plate slot 34 fits between sleeper pieces 31and 32 and defines a loop 35, which is as long as the thickness of thesleeper pieces and into which the tubing 1 fits at installation. Theplate is made of highly thermally conductive material such as aluminum,copper or steel. For example, it can be made of a sheet as thin as 0.008guage, 3003 alloy aluminum; and is attached to sleepers 31 and 32 by asuitable glue or epoxy. The slot 34 formed in such sheet aluminum can beeasily distorted as the spacing between the two sleepers varies. Toavoid this, a piece of reinforcing mat 36 is attached to both sleeperpieces, bridging the space and so insuring a degree of lateraldimensional stability of the module piece parts. The mat 36 may be fiberglass reinforced flexible material that is attached by glue or epoxy tothe sleeper pieces as shown. The completed modular piece 30a, shown inFIG. 15 is substantially rigid longitudinally and can flex slightlyalong the slot 34.

Plate 33 can also be made of heavier thermally conductive material sothat it conducts heat from the tubing more readily. However, it isuseful that the slot 34 loop 35 be continuous with the rest of the plateand if the plate material is relatively heavy, it will likely be morerigid and so the modular piece 30a will not be so flexible along theslot thereof.

For installations in wood frame construction where the spacing betweenfloor joists and between wall studs is 16 inches on center, the modularpiece size is made in consideration of that usual joist and studspacing. For example, for the under floor installation shown in FIGS. 7to 13, two modular pieces must fit side by side in a bay between floorjoists and the bay width is about 141/2 inches. Therefore, the preferredwidth of the modular piece 30a is less than half of that, or between 6and 7 inches. The length of the modular piece is preferably a wholemultiple of 16 inches and preferably 32 or 48 inches.

The inside edges of the sleeper pieces define the space into which theslot in the plate fits. Those edges 47 and 48 may be parallel to eachother and perpendicular to the plane of the modular piece as shown inFIGS. 14 and 16; or they may be beveled as shown in FIG. 17. The purposeof the bevel is to shape the slot in the plate by tapering it so that itis slightly more narrow at the open end (the top as shown in FIGS. 12 to20) where the tubing enters it and widens slightly toward the bottomthereof where the tubing is contained. For example, in FIG. 17 thesleepers 34 and 42 inside edges 47 and 48 are beveled so that theydefine a tapered opening into which the slot 44 of the plate 43projects. Since the sleepers shape the slot, the slot tapers from itsentrance to its bottom and the reinforcing mat 46 fixes the width of theslot at the top when the sleepers are co-planar and that width is fixedto be slightly less than the outside diameter of the tubing 1. As aresult, the tubing must be forced into the slot; and once forced, inremains firmly held so long as the two sleepers are co-planar. Thetubing can be released easily by simply flexing the module at the slotso that the sleepers are not co-planar and the top of the slot is widerthan the bottom.

Second Embodiment Modular Piece Slot Configurations

FIGS. 17 to 19 show variations of the same structure revealed in FIG. 16with straight or tapered walls defining the slot in the heat transferplate that accommodates the tubing. FIG. 18 shows perpendicular sleeperwalls 57 and 58 and the thickness of the sleepers is significantlygreater than the tubing outside diameter, so that the plate loop 55 inslot 54 is deeper and the tubing is sure to be positioned in the slotwith the top of the tubing below the top of the plate.

FIG. 19 shows a configuration that combines the tapered groove of FIG.17 with the deeper slot of FIG. 18. Here, the taper tends to hold thetubing at the bottom of the loop 65 so that the top of the tubing issure to be below the top of the plate.

Filler Around Tubing in First and Second Embodiments

A compliant filler and holding material around the tubing held in thespace 14 in the first embodiment shown in FIGS. 1 to 6 and denotedmaterial 20, and around the tubing in the second embodiment shown inFIGS. 12 to 20 and denoted 40, is applied to the space and/or tubing andis applied to the slot and/or the tubing before the tubing is insertedor forced into the space or slot. A purpose of the filler material is tohold the tubing in the space/slot as an adhesive, while at the same timeallowing the tubing to expand and contract longitudinally within thespaces/slots of successive modular pieces that hold a length of tubingat installation. The tubing must be free to expand and contract, whilethe plates are fixed by staples, nails, screws, etc. to thesub-flooring. Another purpose of the filler material is to reduce noisecreated by expansions and contractions of the tubing in thespaces/slots. Yet another purpose is to provide a medium of thermalconduction from the tubing to the plate; and for that purpose it isimportant that the filler 40 fill all voids between the tubing and thespace/loop of the plate in the slot that contains the tubing. A suitablefiller material for any of these purposes is silicone rubber.

A convenient form of silicone rubber that can be used in theinstallations described herein and shown in FIGS. 1 to 20 is availablecommercially as a sealant or a caulking in viscous liquid form, usuallydispensed from a tube by simply forcing it out of a nozzle on the tube.Such a sealant/caulking is usually a prepared mix of silicone dioxide,methanol and ammonia. A commercial source of this sealant/caulking mixis a General Electric product called SILICONE II that remains resilientfor many years after it is applied.

FIG. 20 shows the same configuration of sleepers 61 and 62, plate 63 andreinforcing web 66 as shown in FIG. 19, (a configuration of the secondembodiment), but with the tubing 1 removed from the slot 64 and poisedfor insertion into the slot. The resilient filler 40 can be applied tothe slot just before the tubing is inserted, or it can be stored in theslot at the bottom of loop 65 thereof and as such, be included with themodular piece such as 30a shown in FIG. 15. In that case, it isrecommended that the filler be protected during storage by, for examplecovering it with a peel off seal, such as seal 69.

RFH--TUBING ON TOP OF SUB-FLOORING

The tubing can be mounted on top of the sub-floor using modular piecessimilar to the first embodiment modular piece 10a, shown in FIG. 5 orthe second embodiment modular piece 30a shown in FIG. 15. FIG. 21 is anenlarged end view of an RFH installation on top of the sub-flooring, 70,showing several modular pieces of the second embodiment, each anassembly of two sleepers, a heat transfer plate and reinforcing web, themodular units being arranged side by side and end to end on thesub-flooring, on an area thereof in a room.

FIG. 22 is a perspective view of the same room showing several of thesecond embodiment modular units of different kinds, arranged side byside and end to end on the sub-flooring 70 of the room over an area ofthe floor defined by vertical corner lines 85a to 85c. The modularpieces hold tubing 1 as a continuous length laid down serpentine fashionfrom piece to piece, embedded in the slots of the modular pieces andheld securely therein by the slot structure itself and the fillermaterial 40 therein.

FIGS. 23 and 24 are perspective views of the several modular pieces ofthe first embodiment of different kinds, that can be arranged as shownin FIG. 22. The long modular pieces 86, in FIG. 22, for holding astraight length of the tubing are shown in FIG. 24. They can be the sameas modular piece 30a shown in FIG. 15, although they do not have to fitside by side within the dimension between floor joists; they can belonger and wider. Here, straight modular piece 86 is comprised ofsleeper pieces 91 and 92, heat conductor/radiator plate 93 having a slot94 that loops into the space between sleepers and reinforcing web 95.

Where the tubing turns at the end of a straight run on the floor,another type of modular piece 87 is used, in which the slot 104 for thetubing turns 180 degrees, as shown in FIG. 23. Unit 87 is comprised ofsleeper pieces 101 and 102, heat conductor/radiator plate 103 having theslot 104 that loops into the space between sleepers and reinforcing web105.

For this on top of the sub-flooring installation, the part of thesub-flooring in the room that is not completely covered by a modularpiece of one type or the other must be brought up to the level of thepart that is covered, by pieces such as 88.

RWH--TUBING HORIZONTAL OVER STUDS

A typical wood frame construction wall structure is shown in FIG. 25 anddenoted 110. It includes a wall sole plate 111, studs 112 to 120 and topplate 121 with several of the straight run modular units 86 and 180degree turn modular pieces 87 shown in FIGS. 23 and 24, arranged side byside and end to end on the studs, providing a horizontal arrangement ofseveral passes of the tubing across the studs and ready for covering bya finished wall covering.

FIGS. 26, 27 and 28 show enlarged side views of the wall, taken as shownin FIG. 25, showing the modular pieces and tubing at a middle stud 116and the end studs 120 and 112, respectively, where the tubing exits andenters the wall from below the sub-flooring. The modular pieces areattached directly to the studs by, for example nailing, with the frontand rear edges extending from the center line of a stud to the centerline of another stud and a finished wall covering 122 is then attachedon top of the modular pieces. FIGS. 26, 27 and 28 show the RWH modularpieces attached to both sides of the studs and so provide RWH from bothsides of the wall formed by the studs.

RWH--TUBING VERTICAL OVER STUDS

The serpentine arrangement of the tubing on a wall can also be vertical.This is shown in FIG. 29, which is a front view of another RWHinstallation showing the same wall 110 having a wall sole plate 111 onthe sub-flooring 70, studs 112 to 116 and top plate 121 with several ofthe modular pieces of different kinds, such as shown in FIGS. 31 to 36,arranged side by side and end to end on the studs, providing a verticalarrangement of several passes of the tubing up and down between thestuds and ready for covering by a finished wall covering 122.

An enlarged side view of the wall is shown in FIG. 30, which showns thetop of stud 114 and the bottom of stud 115, revealing RWH modular piecesattached to the studs on both sides thereof. That Figure shows a modularpiece 131 at the top of stud 114 on one side of the studs and a modularpiece 131 at the bottom of stud 115 on the other side of the studs. Themodular pieces of several different kinds in this RWH installation areattached by nailing to the studs, from the center line of a stud to thecenter line of the adjacent stud and so the width of a piece spans thisspace between studs.

For this kind of installation, each modular piece preferably containstwo slots, one for carrying heating water up the wall and the othercarrying the water down the wall. The several different types of doublemodular pieces for this kind of installation are shown in FIGS. 31 to36. They are double straight modular piece 137 shown in FIGS. 32 and 33;180 degree turn piece 138 shown in FIG. 31; double 90 degree turn piece139 shown in FIG. 36; left, straight, 90 degree turn piece 140 shown inFIG. 34 and right straight, 90 degree turn piece 141 shown in FIG. 35.

The modular pieces 137 to 141 may be constructed with sleepers similarto the second embodiment modular pieces shown in FIGS. 15, 23 and 24 andin that case they can flex laterally along the slots, Such flexingcannot be allowed for this installation, because each piece must spanadjacent studs laterally and provide a rigid lateral surface. To preventsuch flexing, braces 142 are attached on the back of each of the modularpieces 138 to 141.

When the installation shown in FIGS. 29 and 30 is complete, a finishedwall covering 143 is installed on top of the modular pieces by nailingthrough the modular pieces into the studs, being careful when nailingthrough modular pieces 139, 140 and 141, as the tubing crosses a stud atan edge of these pieces. However, otherwise the studs can be nailed intowithout danger to the tubing.

RWH--TUBING VERTICAL AND RECESSED BETWEEN STUDS

FIG. 38 is a front view of yet another RWH installation showing aportion of the same wall 110 that includes sole plate, studs and topplate erected on top of the sub-flooring 70. Several modular pieces ofdifferent kinds, such as modular pieces 137, 138 and 139, shown in FIGS.31, 32 and 36 are used in this installation and as shown are given thosereference numbers. These modular pieces are arranged side by side(separated by a stud) and end and end to end between the studs andrecessed into the space between the studs, providing a verticalarrangement of two passes of the tubing, one up and one down betweenadjacent studs.

All of these modular pieces are held in place on brackets 145 that arenailed to the studs and provide a rigid support at flanges 143a and 143bon each side of the stud for the modular pieces, recessed from thenailing surface of the studs by exactly the thickness of the modularpieces. Notches 144 in the studs accommodate the tubing passing from onerecessed space between studs to the next recessed space between studs.

FIG. 37 is an enlarged top view of wall of taken as shown in FIG. 38,showing the wall studs, modular pieces of different kinds recessed onbrackets 143 that are nailed to the studs and and ready for covering bya finished wall covering 146.

CONCLUSIONS

While the invention described herein is described in connection withseveral preferred embodiments, it will be understood that it is notintended to limit the invention to those embodiments. It is intended tocover all alternatives, modifications, equivalents and variations ofthose embodiments and their features as may be made by those skilled inthe art within the spirit and scope of the invention as defined by theappended claims.

I claim:
 1. In a hydronic heating system having a source of hot supplywater and a reservoir of cooler return water, a supply water line fromsaid source, a return water line to said reservoir and one or moreheating loops through which water flows from said supply line to saidreturn line, said heating loop including a heating element that is alength of tubing that conducts water from said supply line to saidreturn line and said length of tubing is mounted in a wall or a floor ofan area heated by said system by RFH or RWH, respectively, in said area,the improvement comprising:(a) a relatively highly thermally conductiveplate having a radiating surface mounted in said area floor or wall,adjacent a surface thereof, (b) means attached to said plate providingan elongated space for holding said length of tubing adjacent said plateand (c) a compliant filler of relatively high thermal conductivitymaterial that fills around said tubing between said tubing and saidplate, (d) whereby said plate is heated by conduction of heat from saidtubing and (e) said plate radiating surface radiates heat to said area.2. A hydronic heating system as in claim 1 wherein:(a) said meansattached to said plate providing an elongated space for holding saidlength of tubing adjacent said plate is highly thermally conductive andis in intimate thermal contact with said plate.
 3. A hydronic heatingsystem as in claim 2 wherein:(a) said means for holding said length oftubing adjacent said plate is an integral part of said plate.
 4. Ahydronic heating system as in claim 2 wherein:(a) said means for holdingsaid length of tubing adjacent said plate is an integral part of saidplate and the same material as said plate.
 5. A hydronic heating systemas in claim 4 wherein:(a) said material is aluminum.
 6. In a hydronicheating system having a source of hot supply water and a reservoir ofcooler return water, a supply water line from said source, a returnwater line to said reservoir and one or more heating loops through whichwater flows from said supply line to said return line, said heating loopincluding a heating element that is a length of tubing that conductswater from said supply line to said return line and said length oftubing is mounted under the subfloor between the floor joists of an areaheated by said system by RFH, the improvement comprising:(a) arelatively highly thermally conductive plate having a radiating surfacemounted under said floor, (b) means attached to said plate providing anelongated space for holding said length of tubing adjacent said plateand (c) a compliant filler of relatively high thermal conductivitymaterial that fills around said tubing between said tubing and saidplate, (d) whereby said plate is heated by conduction of heat from saidtubing and (e) said plate radiating surface radiates heat through saidfloor to said area.
 7. A hydronic heating system as in claim 6wherein:(a) said means attached to said plate providing an elongatedspace for holding said length of tubing adjacent said plate is highlythermally conductive and is in intimate thermal contact with said plate.8. A hydronic heating system as in claim 7 wherein:(a) said means forholding said length of tubing adjacent said plate is an integral part ofsaid plate.
 9. A hydronic heating system as in claim 7 wherein:(a) saidmeans for holding said length of tubing adjacent said plate is anintegral part of said plate and the same material as said plate.
 10. Ahydronic heating system as in claim 9 wherein:(a) said material isaluminum.